Optical coherence tomography angiography (OCTA) has been recently introduced for the imaging of microvascular networks in the human eye. Recent investigations using OCTA have been primarily focused on showcasing its applications in visualizing the flow characteristics of microvascular diseases within the macula, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR), the two leading causes of blindness worldwide. In addition, OCTA has documented microvascular abnormalities in other macular diseases such as branch retinal vein occlusion (BRVO), central retinal vein occlusion (CRVO), and macular telangiectasia type 2 (MacTel2). Compared with conventional dye-based angiography, OCTA offers a safer, faster, and more cost effective alternative for ocular imaging of the macular vasculature. Overall, the combination of optical coherence tomography (OCT) and OCTA can present integrated structural and flow information of the human eye in vivo, opening new opportunities for both qualitative and quantitative analysis of ocular diseases.
Optical microangiography (OMAG) is one of the many OCTA approaches that utilizes the intrinsic properties of particles' (e.g., red blood cells) motion, to highlight the contrast between signals due to RBCs and signals due to static tissues. Unlike other OCTA approaches such as speckle variance, split-spectrum amplitude decorrelation angiography (SSADA), and phase variance, OMAG is able to harness motion information to the fullest extent by exploiting both amplitude and phase information contained within the OCT signals. Therefore, OMAG is able to produce OCT angiography with better vascular connectivity, higher signal-to-noise ratio (SNR), and higher sensitivity to capillary blood flows. Consequently, OMAG is being established as a valuable tool for the investigation of ocular diseases both qualitatively and quantitatively.